Child safety seats are employed for safely transporting children in vehicles, in particular in cars. There is a large variety of child safety seats adapted for transporting children of different age ranges. In Europe, with standards ECE R 44/03 and ECE R 44/04 a system of groups has been established for categorizing child safety seats. This system ranges from “Group 0” seats suitable for newborn children via “Group 1” and “Group 2” seats up to “Group 3” seats suitable for children up to twelve years old. Based on these basic groups there exist additional groups like “Group 0+” or extended groups like “Group 1-2”, “Group 2-3”, or “Group 1-2-3”. Besides the age of a child, other factors that have to be taken into account when choosing a child safety seat for a specific child include the weight and the height of the child.
Group 2-3 child safety seats or comparable child safety seats are suitable for children with a weight in the range of 15 to 36 kg which approximately corresponds to an age in the range of about 4 to 12 years. Conventionally, child safety seats of this type are not equipped with an integral harness system for securing a child seated in the child safety seat. Instead, a child seated in such a child safety seat is secured to the child safety seat with one of the safety belts provided in the vehicle the child safety seat is placed in. If, for example, the child safety seat is placed on the left backseat of a vehicle, a child sitting in the child safety seat will be secured for transport with the safety belt associated with the left backseat. In conventional vehicles, this safety belt is a three-point belt, i.e. a belt comprising a lap strap and a shoulder strap. The lap strap is designed to be guided across the lap of a vehicle occupant's lap, whereas the shoulder strap is designed to be guided diagonally across one of the vehicle occupant's shoulders, over the chest, and down to a buckle where it meets the lap strap.
In some Group 2-3 child safety seats the vehicle's safety belt is used both to secure the child to the child safety seat and to fasten the child safety seat to one of the vehicle's seats. In other Group 2-3 child safety seats the vehicle's safety belt is used exclusively to secure the child to the child safety seat, whereas dedicated means, such as the loops and latches of the ISOFIX system, are used to fasten the child safety seat to one of the vehicle's seats. The present invention relates to both types of Group 2-3 child safety seats. With both types, the child safety seat serves as a means to raise the child in order to adapt its height to the geometry of the safety belt of the vehicle. Therefore, these types of child safety seats are often referred to as “booster seats”.
Group 2-3 child safety seats are designed to be mounted in a vehicle in a forward-facing orientation, i.e. in such a way that a child positioned in the child safety seat faces the front of the vehicle carrying the child safety seat (provided that the vehicle's seat the child safety seat is placed on itself is forward-facing). Therefore, when such a child safety seat is installed in a vehicle, the backrest of the child safety seat rests on the backrest of the vehicle's seat the child safety seat is placed on. Due to this orientation of the child safety seat, in a frontal crash of the vehicle carrying the child safety seat, the crash-induced displacement of a child sitting in the child safety seat towards the front of the vehicle is suppressed only by the safety belt of the vehicle that is used to secured the child in the child safety seat. Since the seat belts of a vehicle are adjusted to the anatomy of an adult, however, these safety belts are not fully optimized for restraining a child in a child safety seat. In particular, the head excursion experienced by a child sitting in a child safety seat during a frontal crash and the loads applied to the child during the crash cannot be controlled sufficiently with many conventional child safety seats.